Adjustable valve control mechanism for tractor mounted loaders



Nov. 3, 1964 D. R. MUELLNER ETAL 3,155,252 ADJUSTABLE VALVE CONTROL MECHANISM FOR TRACTOR MOUNTED LOADERS Filed June 7, 1963 2 Sheets-Sheet l INVENTORS. 25 DONALD RMUELLNER JoHN R. MUNTJAN or;

ATORNEYS Nov; 3, 1964 D. R. MUELLNER ETAL ADJUSTABLE VALVE CONTROL MECHANISM FOR TRACTOR MOUNTED LOADERS Filed June '7, 1963 2 Sheets-Sheet 2 INVENTORS. DONALD RMUELLNER BYJOHN R. MUNTJANOFF TTORNEYS United States Patent 3,155,252 ADJUSTABLE VALVE CGNTROL MECHANISM FOR TRACTOR MUUNTED LOADERS Donald R. Muellner, Naperville, and John R. Munt anoif,

Aurora, 111., assignors to Caterpiilar Tractor (10., Peoria, IIL, a corporation of California Filed June 7, 1963, Ser. No. 286,320 4 Claims. (Cl. 214-140) This invention relates to adjustable means for automatically controlling the height to which a loader bucket is raised by effecting release of detent mechanism wh1ch holds a control valve in its, bucket-raised position.

. Operation of present day earth moving equipment requires operator attention to numerous controls in addition to driving of the tractor upon which the equipment is mounted. For example in a tractor mounted loader bucket, after the bucket is loaded by crowding into the material to be handled it must be racked back to a carry position by operation of one valve, then raised by lift arms which are pivotally attached to the tractor by operation of another valve, then transported by manipulation of the tractor control and thereafter dumped also by operation of a valve. Raising of the bucket requires time and attention of the operator to insure that the motion of the lift arms is stopped when the bucket has attained a proper height. Consequently operator time and the duration of a complete operating cycle can be shortened by means for automatically discontinuing the raise cycle or stopping the bucket at a predetermined height. Such a mechanism is shown for example in our assignees copending application of Robert G. Mclndoo for Trip Mechanism for Automatically Positioning Vehicle Loaders, filed July 9, 1962, Serial No. 208,303.

It is desirable that a bucket be raised only to a predetermined height which varies during different operations.

For example in loading a truck or bin, the bucket should be raised only to the height for convenient dumping to insure that all of its contents are deposited in the truck or bin without the necessity of lowering the bucket before dumping its contents. Furthermore in operating in mines, tunnels or other locations with height limiting overhead structures, a limit is imposed upon the height to which the bucket is raised. In many operations, it is essential that the height at which the bucket is stopped be varied many times during the day and it is, therefore, desirable that the means for adjusting the height and controlling mechanism be readily available to and easily operable from the operators station. I

It is the object of the present invention to provide an automatically operating and infinitely variable bucket height adjusting means for a bucket loader meeting the above requirements through simple and positively actuating mechanisms.

Further objects and advantages of the invention and the manner in which it is carried into practice are made apparent in the following specification by reference to the accompanying drawings.

In the drawings:

FIG. 1 is a view in side elevation of the front portion of a tractor mounted bucket loader of a conventional type with the adjustable valve control mechanism of the present invention in place thereon;

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In FIG. 1 of the drawings, a tractor is partially shown at 10 as having an operators station, generally indicated at 11. A loader bucket 12 is pivoted as at 13 to the forward ends of a pair. of lift arms, one of which is shown at 14. The lift arms are pivoted to the tractor as at 15 so that they maybe operated between the lower position indicated in full lines and their raised position shown in broken lines by means of hydraulic jacks, one of which is shown at 16. Tilt linkage, generally indicated at 17, is operable in a well known manner, not necessary to an understanding of the present invention, for tilting or varying the angularity of the bucket about its pivotal connection 13 with the lift arms.

The present invention includes a master cylinder shown at 18 in FIGS. 1, 2 and 3 with a piston 19 reciprocably mounted therein and having a piston rod 20 pivotally connected at its outer end at 23 with a bracket 21 fixed with respect to the frame of the tractor to which it is secured as by cap screws shown at 22. The cylinder 18 is pivotally connected to one of the lift arms 14 by adjustable means presently to be described in detail, the pivotal connection being in the form of a shoulder screw 25 shown in FIGS. 2, 3 and 4. Consequently upon raising movement of the lift arms 14, the pivot screw 25 describes an arcuate path about the center of the pivot point 15 between the lift arms and the tractor moving from the position shown in FIG. 2 to that shown in FIG. 3. During the initial part of this arcuate travel of the pivot point 25, it moves a short distance toward the pivotal connection 23 of the piston rod causing relative inward movement of the piston and cylinder. The entire cylinder is filled with hydraulic fluid and this inward movement is permitted by ports, one shown at 26 in the head end of the cylinder and one shown at 27 which is in the rod end of the cylinder when the piston is advanced as shown in FIG. 2 and both communicating between the cylinder and a reservoir 30 for hydraulic fluid adjacent thereto.

Thus upon inward movement of the piston from the position shown in FIG. 2, fluid is free to flow between the head end and rod end of the cylinder. Upon con tinued upward movement of the lift arms 14, and when the pivot point 25 passes through a line between pivot points 15 and 23, the arcuate path recedes from the pivotal connection 23 between the piston rod and the bracket 21 so that the elfective movement of the piston in the cylinder is toward the right as viewed in FIGS. 2 and 3. This movement is also accommodated by the ports 26 and 27 whlch permit flow of fluid between the head and the rod ends in the cylinder until such time as the piston passes the port 27 as shown in FIG. 3 when the fluid in the rod end is subject to pressure and this pressure is communicated through a line 32 to a slave cylinder as shown at 33. This slave cylinder is associated with a spool valve which controls raising and lowering of the lift arms and includes detent mechanism for holding the spool of the valve in the position to which it is moved for raising the lift arms. Such spool valves are well known, one being shown in the copending application referred to above and another in Our assignees copending application of Henry E. Beck entitled Automatic Positioning Device for Material Hold- 7 ing Bucket, Serial No. 78,631, filed December 27, 1960.

For the purposes of the present invention, it will suifice to know that the spool of such a valve, a portion of which is shown at 34, has a notch 35 engaged by a detent 36 when the spool has been shifted toeifect raising of the lift arms by directing fluid to the head end of jacks 16 shown in FIG. 1. The detent 36 is held in engagement with the notch 35 by the force of a spring37 behind a piston 38 in the slave cylinder 33. Thus when pressure rises in the 7 rod end of master cylinder 18, it is communicated to the slave cylinder 33 to retract-the piston and detent against the force of the spring 37 permitting the spool 34 to return to its neutral position under influence of a centering spring (not shown) which forms a part of the spool valve. Excessive pressure in the rod end of the master cylinder 18 is relieved to the reservoir by means of a check valve 39 and a port 40 and any deficiencies of fluid in the rod end of the master cylinder canbe made up through a check valve 41.

In order to vary the height at which the lift arms and bucket are automatically stopped, the distance between the pivotal support 25 of the master cylinder and the pivotal connection 23 is made, adjustable so that the position of the lift arms when the port 27 is closed by the piston 19 is varied. This adjustmentis accomplished by a jack screw 44 mounted for rotation in a bracket 45 and having a hand wheel 46 for effecting rotation thereof. The jack screw has a threaded connection with a nut 48 (see also FIG. 4) to which the slave cylinder is also connected by the screw 25. The nut 48 has an extension 4-9 slidable on a rod 50 which is also carried by the bracket 45 and the bracket is fixed to one lift arm 14 as by cap screws 51. Thus rotation of. the jack screw effects movement of the pivot point, 25 longitudinally of the screw and varies the position with respect to the pivotal connection 23 so that raising movement of the bucket .is stopped at any desired point above a substantially horition of the elevation at which the bucket will automati- 3 cally come to rest. The location of the adjusting means is such that it is readily available to a person at the operators station and thus very easily manipulated.

We claim:

1. In a tractor mounted loader having a bucket supported on lift arms pivoted to the tractor and adapted to be raised by fluid motor means, a control valve for directing fluid to said motor means upon adjustment away from a normal neutral position, means to hold the valve in said position of adjustment and means to release the valve when the bucket attains apredeterrnined height, said last named means comprising, a master cylinder and piston pivoted between a fixed point on the tractor and a point on a lift arm whereby movement of the lift arm creates pressure in the master cylinder, a slave cylinder having a piston operable under pressure to release the control valve, and means for communicating pressure from the master cylinder to the slave cylinder.

2. The combination of claim 1. with a reservoir for fluid communicating with the master cylinder through a port adjacent one end of the master cylinder and a second port intermediate its ends whereby movement of the piston in the cylinder between said ports is free and movement beyond the second port creates pressure.

3. The combination of claim 2 in which one pivotal connection of the master cylinder and piston is adjustable to vary the position at which the control valve is released to stopraising of the bucket.

4. The combination of claim3 in which the adjustable means includes a rotatable jack screw, anut on said screw, and in which one pivotal connection of the master cylinder and piston is carried by said nut.

references (Iited in the file of this patent UNITED STATES PATENTS 3,122,247 Beck Feb. 25, 1964 

1. IN A TRACTOR MOUNTED LOADER HAVING A BUCKET SUPPORTED ON LIFT ARMS PIVOTED TO THE TRACTOR AND ADAPTED TO BE RAISED BY FLUID MOTOR MEANS, A CONTROL VALVE FOR DIRECTING FLUID TO SAID MOTOR MEANS UPON ADJUSTMENT AWAY FROM A NORMAL NEUTRAL POSITION, MEANS TO HOLD THE VALVE IN SAID POSITION OF ADJUSTMENT AND MEANS TO RELEASE THE VALVE WHEN THE BUCKET ATTAINS A PREDETERMINED HEIGHT, SAID LAST NAMED MEANS COMPRISING, A MASTER CYLINDER AND PISTON PIVOTED BETWEEN A FIXED POINT ON THE TRACTOR AND A POINT ON A LIFT ARM WHEREBY MOVEMENT OF THE LIFT ARM CREATES PRESSURE IN THE MASTER CYLINDER, A SLAVE CYLINDER HAVING A 